This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A269071 #7 Jan 18 2019 14:41:12 %S A269071 13,76,521,3288,20400,123976,742688,4397376,25791040,150081504, %T A269071 867569920,4986765312,28523566592,162453499008,921756644864, %U A269071 5212543265792,29388948548608,165253519908352,926962234179584,5188178346090496 %N A269071 Number of n X 4 binary arrays with some element plus some horizontally, diagonally or antidiagonally adjacent neighbor totalling two not more than once. %H A269071 R. H. Hardin, <a href="/A269071/b269071.txt">Table of n, a(n) for n = 1..210</a> %F A269071 Empirical: a(n) = 12*a(n-1) - 40*a(n-2) + 8*a(n-3) + 92*a(n-4) - 32*a(n-5) - 64*a(n-6) for n>7. %F A269071 Empirical g.f.: x*(13 - 80*x + 129*x^2 - 28*x^3 - 20*x^4 - 48*x^5 + 4*x^6) / (1 - 6*x + 2*x^2 + 8*x^3)^2. - _Colin Barker_, Jan 18 2019 %e A269071 Some solutions for n=4: %e A269071 ..1..1..0..0. .1..0..0..0. .0..0..1..0. .0..0..0..0. .0..0..0..1 %e A269071 ..0..0..0..0. .0..0..1..0. .1..0..1..0. .0..0..1..0. .1..0..0..0 %e A269071 ..1..0..0..0. .0..0..0..0. .0..0..0..0. .0..0..0..0. .0..1..0..0 %e A269071 ..0..0..0..1. .0..0..1..1. .0..0..0..0. .0..0..0..0. .0..1..0..1 %Y A269071 Column 4 of A269075. %K A269071 nonn %O A269071 1,1 %A A269071 _R. H. Hardin_, Feb 19 2016